Apparatus for demonstrating and illustrating wave motions.



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APPLIUATION rum un 1v, 1905.

903,074. Patented Nov. 3, 1908.

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C. FORBES. APPARATUS P011 DBMONSTBATING AND ILLUSTRATING WAVE MoTloNs.

APPLICATION FILED HAY 17, 1905.

Patented Nov. 3, 1908.

2 SHEETS-SHEET 2.

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UNITED STATES PATENT OFFICE.

CHARLES FORBES, 0F NEW YORK, N, Y.

Specification of Letters Patent. Application filed May 1'7, 1905.

Patented Nov. 3, 1908.

Serial No. 260,913.

To all whom it may conce-rn:

Be it known that I, CHARLES FORBES, a citizen of the United States, residing at New York city, in the county of New York and the State of New York, have invented an Improvement in Ap aratus for Demonstrat ing and Illustratingl) 7ave Motions, of which the following is a specification.

My invention is an apparatus stration of the formation and pro agation of water or surface waves, waves o condensation and rarefaction, as sound waves, and transverse waves, as the ether waves of light, heat, and electricity. The construction and operation of the a paratus are as hereinafter described, and il ustrated in the accompanying drawings in which Fi ure 1 is a face or front view, and Fig. 2 a bac or rear view, ofthe apparatus. Fig. 3 is an enlarged vertical section of the apparatus. Fig. 4 is mainly a diagrammatic view illustrating the movement or operation of the parts which illustrate the three general classes of wave motion before referred to. Figs. 5 and 6 are perspective views illustrating the certain details of the apparatus,

The principal feature of my apparatus (see Figs. 1 and 4) is a series of wave-motion indicators, constructed, in this instance, in the form of metal disks, those marked W for undulating surface or water waves, S for radial sound or air waves, and E for transverse or ether waves. These disks are connected with a bar or rod 1 to which such movement is im arted as required to cause the upper dis s W to describe an elli se, the middle disks S to move horizontaly in a straight line, and the lower disks E to reciprocate ver tically.

As shown in Fig. 1, a series of rods 1 and their connected disks is arranged on a vertical su porting frame F, to which rods the reqlpire movement is imparted by cranks and t e mechanism arranged chiefl on the back of the said frame, as shown in igs. 2 and 3.

The upper end of each rod 1 is pivoted to a crank 2, which is in turn ixed on a rotatable shaft 3 that passes transversely through the irplper portion oi the frame or support F.

e lower end of each rod 1 is provided with a loop 4, as shown in Fi s. 3 and 5, and is thus connected with, an adapted to slide on, a vertical guide 5, formed o a stout wire Whose ends are bent at right angles and parfor demon allel to each other, so that they may be inserted in the base portion of the frame. The upper disks W, and the lower disks E are fixed on the rods 1, and the middle disks are loosely connected therewith, the same. being provided on the back, as shown in Figs. 3 and 5, with a horizontal {iange 6 havin an opening through which the rod slides. his iiange 6 pro'ects into a groove 7 (see Figs. 3 and 6) whic is formed by spacing apart of two wooden bars 8 that are screwed to a metal back plate 9.

It will now be apparent that if rotation be imparted to the short shafts 3, the rods 1 will be operated to change the position of the disks as indicated diagrammaticall in Fig. 4; that is to say, the upper disks W will describe an ellipse, the middle disks S will move horizontally, and the lower disks E will reciprocate vertically. In this manner, the undulatory movement of water waves will be illustrated by the upper disks, movement of sound waves, which are propagated in the form of concentric s heres, will be illustrated by the disks S, an the transverse vibration of ether waves by the disks E. ln this instance, l have represented thirteen rods l with corresponding sets of disks, in Fig. 1, and all the cranks 2 connected therewith are arranged at 45 to one another. This number of rods and disks serves to Jform one and one-half complete wave to each set as represented by the several disks W, S, E.

`he number need not be limited to thirteen,

but when this number is employed, the cranks 2 must be arranged at t e angle speciiied.

It is apparent that by the operation of all the rods and disks simultaneously, the formation of the three general classes of wave motion are illustrated simultaneously, the elliptical motion indicating the advance of a water crest tending to form breakers, and the recession of the trough tending to Jform the undertow; the disks S, also approach and recede from each other to indicate waves of condensation and rareiaction, while the transverse vibration oi' the disks E indicates transverse vibration representing the production of light, heat, and electric waves.

The same disks may also be used to indicate l the rogressive undulations of an undulating corr l It will be further noted that the apparatus the radial admits of a ready com arisen of similar phases in the three kin s, or systems, of wave motion.

A change in the amplitude of vibration of sound waves may be indicated by lowering the support 8-9 by which the disks are guided. To this end, I extend. the metal backing 9 of the guide 8, as indicated in Fig. 6, and such projecting part 9a enters vertical grooves 10 (see Figs. 1 and 2) which are 'ormed in the end bars or posts of the frame F.

In the position shown in Figs. 1 and 3, the support 8-9 rests upon sirlng-catches 11, whose free ends project back through slots in the frame. It is obvious that by drawing back the catches 11, the su )port 8-9 may be lowered so as to rest on t e lower, or base, portion of the frame, and this will obviously result in limiting the to-and-fro movement of the disks S, or, in other words, cause them to indicate a. less amplitude of vibration.

It will also be seen that if the distant end of the support 8`9 be lowered below the other, there will be a decrease in the amplitude of vibration, and consequently in the loudness of sound. It will be further seen that the phases of the three sets of waves are coincident throughout, for exam le, the condensation of the sound waves fo lows, or eoincides with, the crest of the water and ether waves.

Any one or two of the three rows of disks may be covered so that the third row or set may be observed alone. For this purpose I employ covers, or boards, 18; see Figs. 1 and 2. When not in use, the same are supported on the top of the frame by means of screw pins 19 that pass through holes formed in the oards or covers. When it is desired to use one or both of the covers, they are su ported upon pins 2() that project horizontally from the front sides of the posts f. Thus one cover may be applied over the disks E constituting the lower row or set, and another over the middle row or set S, in which case the upper row or set, indicated by W, would be alone visible.

It remains to describe the mechanism on the back of the frame, as indicated in Fig. 3, by which simultaneous movement is imparted to all the shafts 3, as before described. The rear ends of the shafts 3 are provided with xed cranks 12 all of which are parallel and connected with a horizontal bar 13, which is always held parallel to itself while rotating a crank. To secure this parallelism, I employ what might be called a double parallel-rule mechanism, the same consistin of two sets of bars 14, 14", and a connecting ar 15. The bars 14 are pivoted to the bar 13 near its ends and thelr lower ends are piv- Ued te bars 14@ by bar 15. The bars 14EL are ivoted at their lower ends to the frame A ear 16 is mounted on the shaft 3 of one of t e cranks,

a pinion 17 engages the gear 16 and a grooved pulley 17 is attached. to the shaft of the pin ion and provided with a handle by which it may be used as a crank for rotating the pinion and thereby the year 16. The groove in the pulley (indicateda by a dotted line) permits the application of an endless band extended to any suitable motor.

It will new be apparent that, by rotating the crank 18, all the cranks 12 will be rotated together, and thereby like rotation will be imparted to all the shafts E of the several rods 1, with the result of shifting the position of the disks W, S, E, as before described. It is possible to produce this operation without the use of the gear 1G and the pendant and crank connected therewith, by taking hold of the bar 13 with the thumb and finger and swinging it on the pivots 3.

What I do claim as my invention, and dcsire to secure by Letters Patent, is-

1.. A wave motion apparatus having a mechanism producing three forms of wave motions, with coincident phases.

2. In a wave motion apparatus, having a mechanism producing three forms of wave motions; wave-representing disks in combination with'a contrasting supporting background and an inclosing framework.

3. In a wave motion apparatus having a mechanism producing three forms of wave motions wave-representing disks in combination with vertical controlling connecting rods.

4. In a wave-motion apparatus, the combination with a supporting frame, of a series of rods adapted for vertical and swinging movement and indicators attached thereto, and means connected with the rods at a point below their upper end whereby the indicators are caused to describe ellipses.

5. In a wave-motion apparatus, the combination with a supporting frame having a horizontal guide, of a series of indicators, and means for imparting a to-and-fro movement to said indicators for representing the propagation of sound waves.

6. In a wave-motion apparatus, the combination with a frame having a horizontal guide, of indicators for sound waves and means for imparting to-and-fro movement thereto, the said uide being adjustable vertically corresponrIing to a desired indication of change in amplitude of vibrationpf sound waves.

7. In a wave-motion apparatus, the combination with a supporting frame having a horizontal guideway, of a series of disks having projectlons working in such guideways, a vertical rod which is slidable in such disks, its lower ends being slidable vertically and disks attac-hed to both its apre-r and low-er ends, and means connected with the upper portion of said rod for im arting the desired differential movements ofp the disks.

dicators, and means for reciprotaiitinr said g rods whereby the indicators are inoved to illustrate transverse or ether waves.

10. In a wave-motion apparatus, the coinbination with a supporting fi'aine, of vertical rods, and disks connected therewith for illus-- trating?r Wave motion, of cranks on which the rods are hung, transverse shafts carrying such cranks, other cranks ti'Xed on the oppo i site ends of said shafts and arranged on the rear Side of the frame, and incans for eonneeting and holding the rear cranks parallel.

1l. In a Wave-motion apparatus, the conibination, with a supporting frame, of vertical rods and disks connected therewith, cranks on which the rods are hung, transverse shafts to which the cranks are attached, other cranks 12 l'iXed on the opposite or rear ends of said shafts, and a bar 13 connecting such i cranks and holding them parallel, and. the parallel-rule mechanism consistingy of two sets of bars 14, tta, and a har 15 connectinpr thc meeting ends ot sneh bars, arranged and operating as described.

l2. ln a wave-motion apparatus, the cornbination with a supporting traine, of a series of vertical rods whose lower ends are guided vertically, disks attached to the upper ends of said rods, cranks pivotally connected with the rods at points below said disks and arranged in succession at an angle olf 450 to each other, and nieans for rotating said cranks, whereby the elliptical inoveinent ol' water-waves and formation ol a crest and recession. illustrated.

123. A wave-motion apparatus comprising a vertieal traine having 'uprights provided with forwardiy projecting pins 2U, a series of vertical rods and sets of disks attaelnfld thereto in transverse rows, and coversconsisting ol'4 boards provided with holes corresponding in location to the distance between the pins ola the uprights wherebvvr theyv are adapted to be lmnpY thereon for eoi'ieealing a row of disks so that another row may be observed withont confusion, as shown and described.

In testimonyY whereof, 1 have signed my naine to this specilication in the presence of two subscribing: witnesses, this 11th day ol May 1905.

CHARLES FORBES.

ldritnesses:

(tirantes C. Tnownnloon, lL. s] ALLEN ll. NntsoN. li.. s.j 

